Heat and sound insulating cast product and method of making same



Aug. 26, 1930. w. K. NELSON HEAT AND SOUND INSULATING CAST PRODUCT AND METHOD OF MAKING SAME Filed July 2,' 1927 3 Sheets-Sheet 1 6, 1930. w. K. NELSQN 1,773,841

HEAT AND SOUND INSULATING CAST PRODUCT AND METHOD OF MAKING SAME Filed July 2, 1927 3 Sheets-Sheet 2 H4 J6 4 10 J6 l5 g g 2 4:7 7/ 38 i 29 515 a 26 '28 5/0 29 z:w1awwww aw fiWMWWM EWWW;wwwwwsm1w= ew yz J 1? 5:11, a? 51 lliv Aug. 26, 1930. w. K. NELSON ,8

HEAT AND SOUND INSULATING CAST PRODUCT AND METHOD OF MAKING SAME Filed July 2, 1927 3 Sheets-Shegt 3 0U I IJ LN IHN IHIII' M Patented Aug, 26, 1930 UNITED STATES WILLIAM K. NELSON,

PATENT OFFICE OF CHICAGO, ILLINOIS HEAT AND SOUND INSULATING CAST PRODUCT AND METHOD OF MAKING SAHE Application filed July ,2,

My invention relates to heat and sound in sulating cast products and methods of producing the same.

It is one of the objects of my invention to provide a new and improved product which shall have superior heat and sound insulating qualities, which shall have greater strength in proportion to its weight than that of the prior products, and which can be made to better advantage. I prefer to make my improved product by a casting or molding operation in the form of a. central body portion of cellular mineral matter which has been aerated materially so as to be of compara- :7- tively great porosity, with two outside body layers formed of a material of comparatively greater density or lesser porosity and with fibrous sheets of material interposed between the respective outside body layers and the central body portion.

In the use of an insulating product against the transmission of heat it is important to select a material which has a low specific conductivity constant. When such a material is made cellular in texture heat losses are cut down in that convection currents are kept at a minimum and conductivity through the material is reduced. To this extent the more the cells become isolated, thus producing a dead air effect, the less heat losses by transmission will result.

In the use of a product for sound insulation, however, additional factors should be taken into consideration. In some cases, it is important that reflection be as high as possible, as where it is sought to exclude all sound from the outside, while in other cases it is important that reflection be low in orderv elimination of the sound effect Within the insulated room is desired without regard to whether the result is effected by the transmission of the sound wave energy away from the room or by the absorption of the-energy.

For general sound-proofing purposes, I

1927. Serial No. 203,199.

of my improved product, the progress of the waves is impeded and a considerable portion of their energy is absorbed by reason of the friction between the vibrating air and the sides of the cells. The sound waves are then converted into heat energy and, therefore, no longer exist in a free state.

It is another object of my invention to provide in connection with the cast product one or more well defined dense faces within the body which shall have the effect of reflecting sound waves so as to turn them backwardly within the body of the product which is more cellular or less dense for absorptiontherein, and so as to trap a portion of the sound waves between two such dense faces and to reflect them back and forth a number of times until their energy has been dissipated.

It is a further object of my invention to provide a construction comprising a variety of materials having different insulating values, different densities and different elasticities so as to insure effective absorption and stoppage of sound waves of varying pitch and intensity. I accomplish this object y lnterposing fibrous barriers between the respective relatively dense outside body layers and the central body gortion of relatively higher porosity. The brous barriers also serve as reinforcing elements for the several layers of the finished cast product.

It is another object of my invention to provide a construction in which the movement of moisture through the body by capillary attraction is materially cut down, this provision making it possible to use a lighter and more porous body portion without danger under normal conditions of disintegration of such body portion by reason of an excessive absorption of water. This use of a lighter body portion makes it possible to use heavier or denser facing portions without increasing the weight of the cast product as a whole and without decreasing the insulation value. It also makes it possible to increase the water resistant and water-proofing qualities of the cast product, since the heavier and denser outer face portions lend themselves more readily to water-proofing.

It is another object of my invention to improve the method of making cast products of this type in the form of blocks, panels, or slabs.

It is another object of my invention to improve east products of the types specified in sundry details hereinafter pointed out, and likewise to improve the method of producing the product in the respects indicated by the following description.

The preferred means and methods by which I have accomplished my several objects are disclosed in the specification by reference to the accompanying drawings. What I believe to be new and desire to cover by Letters Patent is set forth in the claims.

In the drawings;-

Fig. 1 is a perspective view of my improved block;

Fig. 2 is a top plan view showing more or less diagrammatically one form of apparatus for producing my improved blocks; 7

Fig. 3 is a vertical sectional view on an enlarged scale, taken substantially at line 33 of Fig. 2;

Fig. 4 is a vertical sectional view taken at line 44 of Fig. 3;

Fig. 5 is an enlarged detail view, partly in section, showing one of the cam devices by which one of the adjustments of the mold is Fig. 6 is a vertical cross sectional view through a form of mold adapted for producing my improved block, being shown with two sheets of fibrous material therein and a funnel position thereon ready for the initial pouring operation;

Fig. 7 is a view similar to Fig. 6 but showing the mold in changed condition ready for the second pouring operation for completing the partially formed block, and with a difierent form of funnel in position thereon; and

Fig. 8 is anenlarged detail view, being a section on line 88 of Fig. 6.

Referring now to the form of block shown in Fig. 1, 17 indicates an intermediateilayer of porous cellular material having sheets of paper or other fibrous material 18 and 19 adhering thereto upon its opposite faces, the layer 17 having been formed by castin between the sheets of fibrous material as ereinafter described. Upon the outer faces of the sheets of fibrous material 18 and 19 there are additional layers 20 and 21 of porous cellular material, these layers also being preferably cast in contact with the sheets 18 and 19, the sheets being preferably perforated at intervals for increasing the bonding eifect and the perforations preferably being staggered so as to avoid material weakening of the sheets. The layers 20 and 21 are preferably similar to the layer 17 except that the material is preferably of considerably greater density than that of the body 17.

In the preferred form of cast product as shown in Fig. 1, the ends and one side of the block are provided with grooves 22 so as to provide a space between two abutting blocks into which a suitable binder can be poured for hardening therein for both keying the blocks together and for causing them to adhere to each other.

By the provision of the form of product as described comprising the intermediate sheets 18 and 19, there is a barrier between the air content of one of the body layers and the air content of the adjacent layer; furthermore, the walls of the cells adjacent to the sheets of fibrous material are'substantially continuous and unbroken so as to produce within the body of the-block'a well defined,

even and dense surface adjacent to each face of the fibrous material. 111 many cases, the waves which succeed in passing through one of the sheets of fibrous material and the adjacent dense faces of mineral matter are defiected when they come in contact with the second sheet of fibrous material and the adjacent dense faces of mineral matter, such waves being to a large extent reflected back and forth between the two sheets of fibrous material until their energy is dissipated.

By reason of the strengthening effect of the fibrous sheets mechanically with respect to the cast product, it is possible to give the required strength to the product without providing outside layers of any considerable thickness. It is thus made practical to provide a more porous material for the intermediate body portion 17 without sacrificing unduly with respect to the strength of the product. With such more porous intermediate body portion 17 in use, it is possible to use a considerably heavier and denser outside facing portion without unduly increasing the weight of the block and without decreasing its total insulation value.

By the provision of the alternate layers of different densities as above described, the effectiveness of the product with respect to stopping sound and heat wavesis increased.

By the employment of outside layers of mineral material of maximum weight and density compared with the total weight. of the product, the water resistant powers of the product are considerably increased. The ease of water-proofing the product is correspondingly increased.

Coming now to an improved form of app'aratus for producing my improved prodnot, as shown in Figs. 2 to 5 inclusive, 23 indicates a turn-table of any suitable type rotatable about a heavy shaft 24 byv the a plication of power thereto in any suitable anner. The turn-table 23 is provided with a' ..ter-clockwise direction in Fig. 2, when each of the molds in turn is brought into position underneath the chute 27 a suitable amount of plastic material is delivered from the chute into the mold Without stopping the movement of the turn-table. This is effected either manuall or automatically as may be desired, the delivery being preferably effected tIiy the use of a funnel of the type shown in ig'..6, such funnel also servingto" hold the sheets of fibrous material in position in the mold. c v

The plastic material to be em loyed for the body of the block is prefers. ly in the form of an unstable mass of plastic material of a type adaptedto aerate and form a cellular texture and then to harden in cellular condition. For a material weighing approximately pounds per cubic foot, I have osedlthe following ingredients,1000 pounds of stucco (calcined gypsum) of average good grade, 90 pounds of aluminum sulphate con taining water of crystallization, 35 pounds a: calcium carbonate, pounds of talc,

' ounces of commercial retarder, and 6 pounds of potassium sulphate, all ofsuch ingredients being finely ground and thoroughly mixed in dry state and then added to a suitable quantit of water at the time of use,

As is e turntable continues to move in counter-clockwise direction after the pouring operation, the hardening of the cellular mass proceeds, the rate of movement of the turn table being such that by the time the table has made approximately half of a complete rotation. the material has hardened sufiicient ly to hold its form.

Referring now to Figs. 3, 4 and which show the form of mold employed, 23 indicates one of a pair of slide blocks which are secured in spaced relation to each other upon the upper face oi? the tullhtfible 23, each of said slide blocks 28 being slidabl mounted between undercut cleate 29, as is est shown in Fig.4. Each of the slide blocks 28 is ro vided with a depending rod orbar 30w icli extends downwardly through a slot 31 in the turmtable 2 3, such rod or bar being provided upon its lowere'nd with'a sleeve 32. The sleeves 32 of the two slide blocks 28 of. each moldare connected to each other by means of a rod 33 reversely threaded at its end portions for engagement with the sleeves 32 of the slide blocks which are correspondingly threaded the bar 33 being held rotatably in position with respect to the table 23 by means of a bracket 34 engaging an inte mediate portion ofthe rod. By a rotation of the rod 33 by means of a suitable Wrench engaging a head 35 upon its outer end, the slide plates 28 of the mold are moved toward or from each other as ma be desired.

I Each of the slide blocks 28 has hingedl mounted thereon a side wall member 36 whic i is releasably held in position with respect.

to the slide block 28 by means of a link 37 her and engaging stop members 38 carried by the slide block Each of the side wallmembers 36 is provided with an adjustable face portion 39 "which is-yieldingly held by means of springs 3 in spaced relation with respect thereto. cans is provided for movin the face por tion 39 of the side wall member toward the portion 36 against the act-ion of the springs 40. In the construction shown this means comprises asleeve 41. carried upon the face of the member 39 adjacentto the portion 36, within whichsleeve is rotatably mounted a head 42 which is provided with a pin 43 which engages a diagonally disposed slot 44 in thesleeve 41. The head 42, which is rotatably connected with the portion 36 o l the side wall member is tprovided with a hor adapted in the continued rotation of the turntable to come into engagement with a guide member 49 held in rigid position above the turntable. When the mold reaches a position at substantially 180 from the position of the mixer 26,each oi? the rollers 48 in turn is brought into engagement with a cam portion 50 of the guide 49 serving to move the link 47 toward the left in Fig. 4 for swinging the arms 46 and the shatt'45 in counter-clockwise direction in said i 4 for causing the pin 43 by engagement with the slot 44 01. the drum to move the portion 39 of the side wall member toward the portion 36 against the action of the springs 40.,

The amount of throw of the diagonally disposed slot 44. of the drum 41 is such as to give the side wall portion 39 a movement corresponding in extent to the desired thickness of'the'outer face portions of the block tances apart by the use of the threaded bars 33.

At opposite ends of the side wall memhers, I have hingedly mounted end wall members 51, as is best shown in Fig. l. These end wall members are hingedly mounted directly upon the turn-table, being held releasably in upright position thereon by means of pivotally mounted links 52 which are adapted by engagement with stop members 53 to hold the end walls in engagement with the ends of the side walls of the mold. The stop members 53 are preferably in the form of rings extending about the turn-table 23.

When in the movement of the turn-table 23 the rollers 48 of each mold in turn are brought into engagement with the cam portion 50 of the guide 19, the inner face portions of the side wall members are moved outwardly into spaced relation to the block which by that time is in condition to hold its shape, the side wall members 36 being readily movable out of contact with the sheets of fibrous material, the partially formed block being held in centered position in the mold by its engagement with the bottom and end walls of the mold. The mold is then carried in the continued rotation of the turn-table under the chute 5% of a second mixing device 55 also driven by power from any suitable source. Through the chute 54, there is delivered to the mold upon opposite faces of the partially formed block and between the sheets of fibrous material and the adjusted inner face portions of'the side walls of the mold a second supply of plastic material, the delivery of the material to the mold being controlled manually or automatically as may be desired. Plates 56 are preferably carried by the side wall members 39 at their upper edges for assisting in directing the material from the chute 5a to the space at opposite sides of a partially formed block, and a funnel of the form shown in Fig. 7 may be employed.

The plastic material to be employed for the outer layers of the block is preferably of the same cellular texture as that of the interior body portion except that the ingredients are changed so as to form a considerably stronger and denser product. The material is preferably in the form of an unstable mass of plastic material of a type adapted to aerate and form a cellular texture and then to harden in cellular condition. For a material weighing approximately 32 pounds per cubic foot, I have used the following ingredients,-1000 pounds of stucco (calcined gypsum) of average good grade, 15 pounds of magnesium fluosilicate containing water of crystallization, 15 pounds of calcium carbonate, 3 pounds of commercial retarder, 16-

pounds of potassium sulphate, and 6 pounds of hydrated lime, all of such ingredients being finely ground and thoroughly mixed in a dry state and then added to a suitable quantity of water at the time of use.

As the turn-table 23 continues its rotation in counter-clockwise direction, the side wall members 39 are held continuously in spaced relation with respect to the artially formed block against the action ot the springs 4.0 by means of the guide 49 which extends about the path of the mold to a point at which the facing portions of the block will have become hardened suificiently for holding their form, such point, in the construction shown,

being in fairly close proximity to the mixer 26 by which the material for the next succeeding block is delivered in the manner already described. When the rollers 48 have passed out of engagement with the guide 4.9, at a time when the face portions have become partially hardened as above described, the swinging links 37 and 52 are released from engagement with their corresponding stop means, and the end walls 51 and the side walls of the mold are both turned downwardly upon their hinge connections out of contact with the block within the mold. The block is then removed and the mold is prepared for the succeeding casting operation. The operation of removing the block from the mold and of preparing the mold for another casting operation maybe effected either manually or by suitable power means as may be desired. After the end and side wall members of the mold have been spread downwardly with respect to each other and the block has been removed from the mold a suitable supply of grease is sprayed or otherwise applied upon the inner faces of the wall members, this being effected preferably by the use of a greasespraying device 57 of any suitable type. After the inner faces of the end and side wall members have been properly greased, the members are again raised into operative relation to each other, being held by the links 37 and 52, and the sheets of fibrous material are secured in position upon the inner faces of the parts 38 ready for the succeeding casting operation upon the continued rotationof the turn-table 23. The sheets of fibrous material (the parts 18 and 19 of the block of Fig. 1) are secured in position in any suitable manner upon the inner faces of the side walls of the mold so as to be held in position therein but so as to permit the side wall portions 39 to move out of contact therewith when such side wall mem- JUL? bers are moved outwardly by the cam portion erably thirty inches long, twelve inches wide of any particular form of grease for the preparation of the mold for the casting operation. I have found in practice that very good results are attained with respect to the release of the mold parts from the hardened cast product and also with respect to the preservation of the color of the product by the use of a grease comprising three parts of castor oil and one part of kerosene.

The block shown in the drawings is prefand from two to six or eight inches thick, though I do not limit the invention to such size orshape of product. A block of the length and breadth specified and four inches thick, with each of the outside layers one-half inch thick, produced in accordance with the formulae above set forth and with the fibrous sheets in the form of ordinary wall board paper, weighs approximately 16 pounds. At a gradient temperature of 60 Fahrenheit between the temperatures of Fahrenheit and 105 Fahrenheit, the heat transmissionv from surface to surface through the 4 inch thickness of the block is approximately 3 B. t. u.s per square foot per degree Fahrenheit er 24 hours. The block, therefore, is of satis actory insulating value, and it has sufficient strength to stand up satisfactorily in shipment and in handling for building operations. By reason of the fact that the layers makin up the block are all of uniform thickness t rough the length and breadth of the block and. are uniformly distributed throughout, the heat flow is uniform at all points and the block is devoid of anything like hot or cold areas.

' I have found in practice that blocks can be produced satisfactorily u on a commercial basis by the use of a num er of molds of.

. comparatively simple construction without the employment of a machine of the type .described. A mold of this type is illustrated in Figs. 6, 7 and 8 in which the base of the mold is in the form of a piece of sheet metal 58 of brass or other suitable material, the base as illustrated being provided with turned edge portions 59 serving as supports. Slidably mounted on the base 58, are two side wall members 60, also made of sheet metal in the form illustrated, being provided with strengthening flanges 61 at their upper edges, with supporting base flanges 62 along their bottom edges and with arallel endflanges 63 at their end portions. he base flanges 62 are ofsuch width as to afford a stable support for the side wall members upon the base 58, as well as to provide a close joint between the side wall members and the base.

At each end of the mold, there is mounted an end wall member 64 also in the form of a sheet of metal, pivotally connected at its lower edge with the base 58 by means of hinges 65, so as to fit snugly against the ends of the side wall members 60 when in their raised position and so as to be movable readily out of contact with theside wall memers.

In the construction shown, each of the end flanges 63 is provided with two blocks 66 rigidly secured thereon, oppositely disposed with respect to blocks 67 rigidly mounted on the outer faces of the end wall members 64,

four of such blocks 66 being provided on each of said members 64. Each of the blocks 67 and the adjacent portion of the end wall member is provided with two openings 68, one above the other, as is indicated in Fig. 7 at the point where a portion of one of the flanges 63 is broken away. Each of the blocks 66 and the adjacent portion of the flange 63 is provided with an opening 69 at the same level as that of the upper opening 68, and with two openings 7 O at the same level as that of the lower opening 68, the openings 70 in the construction shown being one inch apart from center to center. A pin 71 is provided for each corner of each end wall member 64, the arrangement in the construction shown being such that when the pins 71 pass through the openings 68 and the outer openings 70 the side wall members. will be held at a distance of two inches from each other; that when the pins 71 pass through the open ings 68 and 69 the side wall members will be held at a distance of three inches from each other; and that when the pins pass through. the openings 68 and the inner openings '36 the side wall members will be held at a distance of four inches from each other.

In the construction shown, the pins 71 are secured in position so as to be readily removable. Each of the pins is provided with a circumferential groove at the end, being cut away at one side so as to permit the pin to pass a plate 72 carried by the block 66, the pin being secured in position in engagement with the plate 72 by a partial rotation of the With the members 60 secured in position at a distance of two inches apart, and with the parts properly greased, two 'sheets of paper or other fibrous material 73 are slipped into position in contact with the faces of the members 60, such sheets of paper being provided preferabl with staggered perforations 74 therethrougli. A funnel is then preferably placed in position, serving to hold the sheets of fibrous material in position as illus trated in Fig. 6, such funnel comprising side wall members 75 connected at their ends by bars 76. With the parts in the positions as above specified, the body of theblock ispoured and is given anopportunit to harden sufliciently to hold its form. he upper edge of the block is then dressed off even with the upper edges of the mold, after which the pins 71 are removed for enabling the side wall memhere to be movedinto spaced relation with respect to the partially formed block, the

block being held in position in the mold by its engagen'ient-with the bottom Wall thereof. In Fig. 7, the partially formed block is indicated by the numeral 77. In the preferred form of practice of my invention for ordinary purposes, the side wall members will be spaced at a distance of one-half inch from the partially formed block at each face thereof. A different form of funnel will then be placed in position, comprising side wall portions 78 connected at their ends by bars 79 which in turn are connected by an intermediate longitudinally extending strip 80, this construction serving to permit material to be poured at each side of the partially formed block while at the same time protecting the edge of the block. After the second pouring operation and the hardening of the block sufficiently for holding its shape, the material is again trimmed off even with the upper edges of the side wall members, and the block is removed from the mold.

By the use of my improved construction, in which intermediate sheets of fibrous material are bonded strongly with the several layers of the body, a substantially monolithic structure is produced, the fibrous sheets being disposed in such a way throughout their entire extent that the efiect due to the tension residing in the sheets is taken advantage of and utilized for reinforcing the block mechanically. At the same time, the maximum of elliciency is attained with respect to the insulating value of the fibrous material in connection with the associated layers of cellular mineral structure. By the use of the several layers of cellular body material with the interposed sheets of fibrous material, changes in the elasticity and density of the parts making up the insulation product are provided, each change in elasticity and density serving to impede the progress ofthe heat and sound waves through the hotly. In the case where the intermediate sheets of fibrous material are introduced within the body of the cast product some distance away from the outside surface an additional advantage results because the fibrous sheets serve as barriers even though cracks or free passages develop in the mineral layers of the product.

While I prefer to employ some such structure as that disclosed by my drawings and as above described, I wish to have it understood that I do not desire to limit my invention to the particular forms of product and' apparatus as shown, nor to the combination of materials as named, except so far as certain of the claims are specifically so limited, since it is evident that changes might well be made without departing from the spirit of my invention.

I claim 4 v1. A. heat and sound insulating cast product, comprising a plurality of layers of cellular material bonded to the opposite faces of an intervening sheet of fibrous material.

2. A heat and sound insulating block, comprising in combination a sheet of fibrous material perforated at intervals, and layers of cellular material at opposite faces of said sheet bonded to the sheet and to each other by connecting tongues extending through said perforations.

3. A heat and sound insulating cast product, comprising two sheets of fibrous material bonded to the outer faces of an intervening body of cellular material, and two other layers of cellular material bonded to the outer faces of said sheets of fibrous material. a. A heat and sound insulating cast product, comprising two sheets of fibrous material bonded to the outer faces of an intervening body of cellular material, and two other comparatively thinner layers of cellular material of comparatively greater density bonded to the outer faces of said sheets of fibrous material.

5. A heat and sound insulating cast product, comprising two sheets of fibrous mate rial perforated at intervals and bonded to the outer faces of an intervening body of cellular gypsum, and two other comparatively thinner layers pf cellular gypsum of com 'paratively greater density bonded to the outer faces of said sheets of fibrous material.

6. T he method of making a heat and sound insulating product having layers of cellular mineral material with a sheet of fibrous material between said layers, which comprises providing connecting tongues formed integrally with the material of one of said layers and extending through perforations in said intervening sheet of fibrous material into bonding relationship with the other layer.

'2'. The method of making a heat and sound insulating product having layers of cellular mineral material with a sheet of fibrous material between said layers, which comprises placing a perforated sheet of fibrous material on edge within a mold, and then filling the spaces at opposite faces of said sheet in said mold and filling the perforations in said sheet with unstable masses of plastic material aerated to form a cellular texture and adapted to harden into stable cellular condition in closely bonded relationship to said. sheet.

8. The method of making a heat and sound insulating product having layers of cellular mineral material with a sheet of fibrous material between said layers, which comprises placing a perforated sheet of fibrous mate: rial on edge within a mold, filling the space at one face of said sheet and filling the perforations in the sheet with a mass of plastic material adapted to harden in closely bonded relationship to said sheet, and filling a space in the mold at the opposite face of said sheet with an unstable mass of plastic material IZU aerated to form a cellular texture and adapted to harden into stable cellular condition in closely bonded relationship with the tongues of material extending through said perforations.

9. The method of making a heat and sound insulating product, which comprises placing a sheet of fibrous material on the inner face of an adjustable wall of a mold, then filling the mold in contact with the sheet with an unstable mass of plastic porous material aerated to form a cellular texture and adapted to remain in a stable cellular condition, then after the mass is in condition to hold its form moving said adjustable wall into spaced relation to said sheet, and then filling the space in the mold between said sheet and said adjustable wall with an unstable mass of plastic porous material aerated to form a cellular texture and adapted to remain in a stable cellular condition.

10. The method of making a heat and sound insulating product, which comprises placing two sheets of fibrous material on the inner faces of adjustable side wall members of a mold, then filling the mold in contact with the sheets with an unstable mass of plastic porous material aerated to form a cellular texture and adapted to remain in a stable cellular condition in bonded relation to said sheets, then after the mass is in condition to hold its form moving said side wall members of the mold outwardly into spaced relation to said partially formed product still held in fixed position by its engagement with the bottom of the mold, and thenfilling the spaces in said mold between said sheets and said adjusted side wall members with unstable masses of plastic porous material aerated to form a cellular texture and adapted to remain in a stable cellular condition.

11. The method of making a heat and sound insulating product, which comprises greasing the inner faces oi the bottom and wall members of a mold in which the side wall members are adjustable toward and from each other, then placing two sheets of fibrous material on the inner faces ofsaid adjustable side wall members, then filling the mold in contact with the sheets with an unstable mass of plastic porous material aerated to form a cellular texture and adapted to remain in a stable cellular condition in bonded relation to said sheets, then after the mass is in condition to hold its form moving said side wall members of the mold outwardly into spaced relation to said partially formed product still held in fixed position by its engagement with the bottom of the mold, and then filling the spaces in said mold between said sheets and said adjusted ,side wall members with unstable masses of plastic porous material aerated to form a cellular texture and adapted to remain in a stable cellular condition.

WILLIAM K. NELSON. 

